1. Field of the invention
The present invention generally relates to an apparatus for delivering fluid to a rotary device, and, more particularly, to a fluid delivery system including a rotary union which is adapted for use in a mechanical press to supply fluid to the crankshaft and which provides damped clearance spaces at its bearing surfaces.
2. Description of the related art
Mechanical presses are generally provided with a frame structure having a crown and bed in which a slide member is supported for reciprocating movement relative to the bed. A crankshaft mounted within the frame structure translates rotary motion generated by a drive mechanism into reciprocating linear activity that is coupled to the slide member through an intermediate assembly of connecting rods. During the press stroke, the upper die mounted to the slide member is brought into pressed engagement with a lower die mounted to a bolster, which in turn is secured to the bed. Mechanical presses of this construction, such as straight side presses and gap frame presses, are widely used for blanking and drawing operations and vary substantially in size and available tonnage depending upon their intended use.
The flywheel assembly serves as the primary source of stored mechanical energy and rotary driving power in the mechanical press. Standard configurations have the flywheel located between the main drive motor and clutch, while being mounted on either the driveshaft, crankshaft, or press frame by use of a quill. The main drive motor replenishes the flywheel with rotational energy as it becomes depleted due to the on-going press stamping operations, during which the clutch engages the flywheel and establishes a driving connection with the crankshaft that acts to draw energy away from the flywheel and convert it into useful mechanical work for powering the press components.
One aspect of mechanical press construction important to its durability and effectiveness concerns whether an adequate lubrication system has been provided to supply the bearing supports with sufficient amounts of pressurized fluid. This concern is vitally important to mechanical presses that rely upon rotary devices such as crankshafts, flywheels, and drive shafts to consistently generate high levels of torquing power necessary to meet the load requirements of the particular industrial application. A two-fold problem exists in attempting to supply oil to these rotary components. First, the rotational motion makes it difficult to transmit oil to the bushing clearance areas from an external source. Furthermore, it is difficult to provide adequate sealing protection to a rotating machine without introducing the risk of friction-related structural degradation, which occurs due to the abrasive contact between the seal and the adjoining rotating surface.
One conventional approach to providing such oil delivery involves the use of a stationary rotary union that supplies oil to the rotating crankshaft. A seal secured to the rotary union is provided at the interface between the rotary union and the adjacent crankshaft in order to prevent fluid leakage. However, as noted above, it is difficult to provide a durable seal in the manner described because the stationary sealing member, which is disposed in abutting contact with the rotating device, is constantly being subjected to frictional pressures that develop due to the sliding contact between the rotating shaft and the intimately coupled sealing member. It is therefore desirable to provide a system for lubricating the bearing supports that incorporates a rotary union but avoids any implementation requiring a sealing member to be placed in direct contact with the crankshaft or other rotary machine surface.
The conventional rotary union attempts to minimize the seal damage arising from frictional influences by employing anti-friction bearings. However, this bearing arrangement presents problems because the free and undamped clearance it establishes with adjacent machine surfaces leads to pounding out of parts when high levels of vibration severity occur during the stamping operation. It is therefore desirable to provide a rotary union that is devoid of any free and undamped clearances.